WASHINGTON (AP) _ Secretary of Education William J. Bennett installed aide Charles H. Karelis as the new director Tuesday of the Fund for the Improvement of Postsecondary Education.

Bennett has been seeking to exert more control over how the program spends its $12.7 million budget. Last week he named five new members to the fund's 15-member national board.

Karelis, 40, who is on leave as chairman of the philosophy department at Williams College, replaces Sven Groennings, who ran the program since 1981 and who reportedly had resisted Bennett's efforts to set new priorities for the fund.

The House of Representatives recently directed Bennett to maintain the fund's autonomy. The program provides seed money for projects in higher education.

Since its creation in 1972 it has helped nurture scores of programs to improve access to higher education for women, minorities, blue-collar workers and non-traditional students.

Bennett was on vacation in North Carolina and unavailable for comment Tuesday. But he said in a statement: ''I have a high regard for Dr. Karelis, who has been advising me on a wide range of matters related to higher education and has served as my liaison with the higher education community. He will make an excellent director of the fund.''

Bennett, a former philosophy professor, and Karelis were fellow undergraduates at Williams in the early 1960s.